Oil pump arrangement for supplying oil under pressure in an internal combustion engine

ABSTRACT

A internal combustion engine lubrication pump assembly (95) having a mounting frame (104) which is received by an aperture (104a) in a gear plate (10) and driven by a radial gear (22)of the engine accessory gear train and further including a method and apparatus for precisely positioning the gear plate (10) on the block (12) of the engine accessory drive gear train (22, 24, 26, 28, 30, 32, 34 and 36) whereby the precise positioning of the gear plate (10) results in the precise alignment of the gears mounted thereon. The present invention achieves this result by utilizing the shafts (56 and 58) of two of the gears (34 and 36) in the gear train as primary and secondary positioning means. Primary and secondary positioning bores (66) are formed in the engine block (12) and in the gear plate (10) and the primary and secondary gear shafts (60) inserted therein to position the gear plate (10) first at a point along a first axis relative to the engine block (12) and secondly at a point along a second axis relative to the engine block (12). The gears (22, 24, 26, 28, 30, 32, 34 and 36) mounted on the gear train are thus maintained in correct alignment relative to the engine crankshaft and camshaft gears (14, 18) and to adjacent mating gears (32, 34, 36, 26). Also disclosed are a mounting arm (88) integral with the gear plate (10) for variably positioning a radial gear (26) which drives the fan clutch assembly (86).

This application is a division, of application Ser. No. 331,799, filedDec. 17, 1981, now U.S. Pat. No. 4,459,950, which is a division ofApplication Ser. No. 104,914, filed Dec. 18, 1979, now U.S. Pat. No.4,321,896.

DESCRIPTION

1. Technical Field

This invention relates to an internal combustion engine gear plateassembly upon which a gear train for driving the engine accessories maybe mounted and properly positioned relative to the engine crankshaft andcamshaft.

2. Background Art

In most applications of internal combustion engines, numerous enginecomponents and accessories must be driven from the engine crankshaft.Such components and accessories include not only those which areessential to engine operation like the camshaft, fuel pump andlubrication pump and air compressor, but also those which are requiredby the particular engine application. For example, a vehicle engine isfrequently required to provide drive torque to a variety of vehicle andengine related accessories such as a hydraulic pump for power steering,refrigerant compressor for an air conditioner and an electricalalternator, a water pump for engine cooling or a fan clutch for acooling fan. Mounting such components and accessories on or adjacent aninternal combustion engine to permit drive torque to be transmitted in aconvenient manner to each of the engine components and accessories isoften a tricky design problem.

In heavy duty internal combustion engines, especially of the compressionignition type, a gear train is normally employed between the crankshaftand the engine components and accessories driven thereby to insureadequate torque transmitting capability. Such gear trains generallyrequire plural idler gears which must also be mounted on the engine,thereby further complicating the problem of providing proper support anddrive to the various engine components and accessories. Due to therotational speed at which the engine components and accessories must bedriven and the rather high torque requirements of such components andaccessories, the individual gears making up the accessory drive trainmust be of very high precision quality. The performance capability ofsuch high quality gearing may not be fully realized unless each gearmaking up the drive train is very carefully positioned to provide propergear lash between the meshing gear teeth. Failure to achieve optimumgear lash can result in severe damage to the gear teeth requiring acostly and time consuming overhaul of the gear train.

A variety of mounting approaches have been developed in an attempt toaccomodate the above noted design requirements. For example, in someengines the accessory drive gears are mounted directly on the engineblock, such as is disclosed in U.S. Pat. Nos. 2,857,773 and 3,502,059.However, mounting the gears directly on the engine block requires themachining of a multiplicity of bores in the block to receive the shaftsof the accessory and idler gears, and these bores must be preciselyspaced relative to the crankshaft, the camshaft and each other. An errorin machining even one bore could result in an unuseable engine blockwhich must be discarded at considerable expense to the manufacturer.Even when the bores are positioned correctly, separate alignmentapparatus is required to achieve proper gear lash. Such gear alignmentapparatus as that disclosed in the aforementioned United States patents,while helpful to obtain correct gear position and maintain the gear lashwithin acceptable limits, necessitates the use of several speciallymachined parts and extensive time consuming maneuvers to achieve therequired gear alignment.

Mounting the accessories and accessory drive gear train on a separateframe or plate which is then mounted on the engine block, such asillustrated in U.S. Pat. No. 1,647,434 to Chorlton, eliminates theprecision machining required to position the gear shaft receiving borescorrectly in the engine block. Gear shaft receiving bores must still bepositioned precisely on the gear plate; however, if a machining error ismade only the gear plate is rendered unusable. The cost to themanufacturer of discarding an incorrectly bored gear plate issignificantly less than the cost of discarding an incorrectly boredengine block. However, the use of a gear plate does not avoid allalignment problems. Once the plate is precisely bored to receive theshafts of the gears to be mounted thereon, the plate itself must bepositioned relative to the engine block to permit accurate alignment ofthe crankshaft and camshaft gears with the other gears of the accessorydrive gear train. In the past this has been a difficult and timeconsuming procedure which had to be performed upon assembly of a newengine and repeated, at least in part, every time the gear plate wasremoved and remounted on the engine. One previously used alignmentprocedure for installing a new gear plate-like structure, described inShop Manual V-1710 C.I.D. 1978, pages 14-11 and 14-12, published byCummins Engine Company, Inc., assignee of the present application,requires the installation of a pair of guide studs on the engine blockfor initially positioning the gear plate and mandrels in the camshaftbores to further fix the location of the plate. Alternately, thecamshafts themselves in combination with an indicator gauge could beused in place of mandrels to obtain true concentricity of the camshaftbores in the block and in the gear plate. After the plate was positionedand the capscrews temporarily installed and tightened, the gears had tobe assembled in position, the gear lash checked, and the gears removedto permit the gear plate to be reamed and doweled. The guide studs werethen removed at this point and the capscrews holding the gear plate tothe engine block tightened to the correct torque. The gears of the geartrain could then be installed and the lash rechecked. If the lashexceeded the minimum acceptable value, the procedure had to be repeateduntil the gear lash was within acceptable limits. Obviously, a procedureof this type is extremely time consuming, thereby significantlyincreasing production and repair expense.

In short, the prior art has failed to disclose apparatus or method forpositioning an internal combustion engine gear plate on which aremounted engine accessories and a gear train for driving such accessorieswhereby accurate plate and gear alignment are achieved with a minimum ofmanufacturing and assembly time and cost.

DISCLOSURE OF THE INVENTION

The basic object of this invention is to overcome the disadvantages ofthe prior art as listed above and, in particular, to provide apparatusand method for simply and precisely positioning a gear plate and theaccessory drive gear train mounted thereon on the block of an internalcombustion engine.

A more specific object of this invention is to provide a gear plate formounting the accessory gear train on the block of an internal combustionengine having primary and secondary positioning bores which align withcorresponding primary and secondary positioning bores on the gear plateto receive the shafts of two of the gears of the gear train, therebyaccurately positioning the gear plate with respect to the engine blockand the gears mounted thereon with respect to the crankshaft andcamshaft gears and each other with a minimum of precision machining andassembly time.

Another object of this invention is to provide a gear plate assembly forsupporting a plurality of engine accessories and for mounting anaccessory gear train on the block of an internal combustion enginewhereby the plate may be precisely positioned with respect to the engineblock by utilizing preexisting structural elements, i.e., idler shaftsand gear shaft receiving bores.

Yet another object of this invention is to provide a method forprecisely positioning a gear plate for mounting the accessory gear trainon an internal combustion engine relative to the engine block whichincludes the steps of machining primary and secondary positioning boresin the engine block, machining corresponding primary and secondarypositioning bores in the gear plate and inserting the shafts of two ofthe gears in the gear train through the bores in the gear plate and intothe engine block.

Other and more specific objects of this invention will become apparentfrom the following Brief Description of the Drawings and Best Mode forCarrying Out the Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a gear plate assembly formed inaccordance with the subject invention prior to the gear plate beingproperly aligned wherein potential misalignment of the gears has beengreatly exaggerated;

FIG. 2 is a front elevational view of the gear plate assembly of FIG. 1after proper alignment has been achieved;

FIG. 3 is a cross-sectional view of the gear plate assembly of FIG. 2taken along lines 3--3;

FIG. 4 is a cross-sectional view of the oil pump assembly mounted on thegear plate of FIG. 2 taken along lines 4--4; and

FIG. 5 is a cross-sectional view of the oil pump assembly of FIG. 2taken along lines 5--5.

BEST MODE FOR CARRYING OUT THE INVENTION

The novel features of the present invention can be best understood withreference to FIG. 1 which illustrates a gear plate assembly 2 includingan accessory gear train 4 mounted on a gear plate 10 which, in turn, ismounted on the engine block 12 of an internal combustion engine. Engineblock 12 may be of the type which includes a main frame 11 mounted abovean oil pan adapter or ladder frame 13, all of which is described in U.S.patent application Ser. No. 22,647, filed Mar. 21, 1979, assigned to thesame assignee as the present application and incorporated herein byreference. The main drive gear or crankshaft gear 14 is mounted directlyon the projecting end of crankshaft 16 rotatably mounted in block 12 andthe camshaft gear 18 is mounted directly on the camshaft 20 which isalso rotatably mounted in block 12. Gear plate 10 includes suitablymachined holes (not shown) to permit passage of the crankshaft andcamshaft therethrough. The accessory gear train illustrated in FIG. 1includes radial gears 22, 24, 26, 28 and 30 which provide drive torqueto various engine accessories and idler gears 32, 34 and 36 whichprovide driving connections between the crankshaft and camshaft gearsand between the crankshaft and one or more of the radial gears. Each ofthese idler gears is rotatably mounted on a shaft journaled in anassembly bolted onto gear plate 10. For reasons which will be explainedin greater detail hereinbelow, the shafts on which idler gears 34 and 36are mounted are formed to project into corresponding bores (not shown)in engine block 12. Each of these bores is connected with thelubrication circuit through internal channels formed within the engineblock 12. As will also be explained in more detail below, lubricationfluid is thus directed to the bearing surfaces of the individual idlershafts to provide continuous lubrication thereof. In the specificembodiment of FIG. 1, gear 22 drives the oil pump, gear 24 drives thewater pump, gear 26 drives the fan clutch, gear 28 drives the aircompressor and gear 30 drives the hydraulic pump with each of the drivenaccessories being mounted directly on plate 10.

If the gear plate 10 is not aligned accurately with respect to thecrankshaft and camshaft the teeth of most of the gears cannot meshproperly. For purposes of illustration only, the effects of gear platemisalignment is illustrated in greatly exaggerated form in FIG. 1,wherein plate 10 has been rotated counterclockwise and displaced to theleft from the properly aligned position (illustrated in dashed lines).

As illustrated, teeth 38 of camshaft gear 18 are so far away from teeth40 of fan gear 26 that there is no contact therebetween as would berequired for engine operation. The misalignment of gear plate 10 of thetype illustrated in FIG. 1 would also result in improper meshing betweenother gear teeth as illustrated in greatly exaggerated form in Figure 1.For example, teeth 42 of crankshaft gear 14 and teeth 44 of idler gear32 would be misaligned as would be teeth 46 and 48 with respect to theteeth of gears 34 and 36, respectively. Yet another problem created bythe improper alignment of gear plate 10 is shown in FIG. 1 by the way inwhich teeth 50 of camshaft gear 18 contact the mating teeth of idlergear 34. Although misalignment of the degree illustrated in FIG. 1 couldnot occur, the amount of torque which must be transmitted through geartrain 4 is such that even a slight misalignment can result in excessivegear tooth wear and possible failure of the gear train.

These and other potential problems are avoided by providing means toposition the gear plate accurately upon installation of the plate on theengine block so that the gears mounted thereon are properly aligned withrespect to crankshaft gear 14 and camshaft gear 18 and that thisalignment is maintained during engine operation and repair. As discussedhereinabove, previously known means, such as that utilized by theassignee of the present application, for achieving this objective haverequired special apparatus as well as long and involved procedures.Moreover, the difficult and time consuming process must be repeated, atleast in part, each time the gear plate is removed and replaced orremounted. The present invention provides apparatus and method forobtaining optimum gear plate and, thus, gear train alignment which issignificantly simplified in comparison to heretofore known apparatus andmethods. As a result, the initial installation of the gear plate and itssubsequent remounting or replacement are no longer the involved, costlyprocedures they once were.

FIG. 2 illustrates the gear plate of FIG. 1 accurately positioned withrespect to the crank-shaft and camshaft so that the gear train mountedthereon is precisely aligned. Dashed lines 54 in FIG. 1 show thecorrectly aligned position gear plate 10 occupies in FIG. 2. It can thusbe clearly seen how a relatively small variation from the required gearplate position could result in the gear malfunction and failurediscussed above. As can be observed from FIG. 2 when the gear plate isproperly aligned, the teeth of mating gears all mesh properly. Byproperly holding manufacturing tolerances on the gear shaft receivingbores (not illustrated) in the gear plate 10, and by also holding theindividual gears and shafts on which each is mounted to predeterminedmanufacturing tolerances, proper gear lash can be assured between allmating gears merely by fixing plate 10 with respect to two indexingpositions with respect to engine block 12.

The manner in which this optimum gear plate and gear alignment isachieved by the present invention is best understood with reference toFIGS. 2 and 3. Gear plate 10 includes suitably machined bores (notshown) for mounting the shafts of accessory gears 22, 24, 28 and 30 andidler gears 32, 34 and 36 as well as openings to accommodate the outwardprojections of the crankshaft and the camshaft. The locations of thesebores is determined by the distances between the centers of adjacentmating gears required to provide gear lash within acceptable limits whensuch gears are formed within preset manufacturing tolerances. Inaddition, as mentined hereinabove, indexing bores in the engine blockare provided to correspond with the bores on gear plate 10 for idlergears 34 and 36 so that the shafts on which these gears are mounted maybe formed to extend in indexing relationship into the correspondingindexing bores formed in block 12.

Briefly stated, the present invention utilizes the shafts of two of thegears in the gear train to position the gear plate correctly on theengine block. Although it is preferred to use the shafts of idler gears34 and 36 for this purpose, the shafts of any two gears may be mountedon the gear plate first to position the gear plate relative to theengine block at a fixed point along a first primary axis and, secondly,to fix the position of the gear plate relative to the engine block at afixed point along a second axis parallel to the first. Only two indexingpoints are required to properly position plate 10 both rotationally andtranslationally with respect to the engine block 12. In the preferredembodiment shown in FIG. 2, shaft 56 on which idler gear 34 is rotatablymounted functions as the primary gear plate positioning means and shaft58 on which idler gear 36 is rotatably mounted functions as thesecondary gear plate positioning means. The holes in gear plate 10 (notshown) through which shafts 56 and 58 are inserted are required formounting gears 34 and 36 on the gear plate, irrespective of anypositioning function the gear shafts might serve. Therefore noadditional machining of the gear plate for guide studs or dowels such ashas been required in the past to achieve correct gear plate position isneeded.

The way in which primary gear shaft 56 mounts gear plate 10 to theengine block is illustrated in detail in FIG. 3, which is across-sectional view of the gear plate and a portion of the engine blockand gear train taken along lines 3-3 of FIG. 1. Primary gear shaft 56includes stationary idler shaft 60 including a positioning projection 62for insertion through primary pilot bore 64 in gear plate 10 intocorresponding primary pilot bore 66 in the engine block 12. AlthoughFIG. 3 illustrates the preferred diametric profile of stationary idlershaft 60 and positioning projection 62, other diametric profiles ofthese structures than the circular, constant cross-sectional profileshown may be utilized. The only requirement which must be satisfied bythe diametric profiles of stationary idler shaft 60 and positioningprojection 62 is that they permit simultaneous mounting of the gear andpositioning of the plate with respect to an indexing position on theengine block. A first pair of thrust bearings 68 and a bushing 70 onidler shaft 60 function to rotatably mount gear 34 relative to idlershaft 60 while simultaneously fixing the axial position of gear 34relative to the engine block. Tab 76 prevents thrust bearings 72 fromrotating. Hole 78 in gear plate 10 accommodates tab 76 of one of thepair of thrust bearings 72 positioned directly against the gear plate.Three mounting bolts 77 (only one of which is illustrated in FIG. 3)secure gear shaft 56 to the cylinder block.

As illustrated in FIG. 3 engine block 12 may include internallubrication channels such as channel 79 into which pilot bore 66 isextended to form a lubrication flow path for the idler gear bearing. Inparticular, idler shaft 60 preferably includes a longitudinallubrication channel 80 and radial channel 81 in positioning projection62 to permit lubricating fluid to be conducted from channel 79, throughchannels 80 and 81 to provide a continuous supply of lubrication fluidto the bearing surfaces of the shaft of idler gear 34.

Additionally shown in FIG. 3 are vibration damper 82 mounted on the endof crankshaft 16 and gear cover 84, which encloses the vibration damperand the accessory gear train. The structure and function of gear cover84 are described in detail in U.S. patent application Ser. No. 974,562filed Dec. 29, 1978 and assigned to the same assignee as the presentapplication.

Radial gear 26 is mounted on the input to the fan clutch assembly 86,illustrated in FIG. 3, to provide driving torque to the fan of theinternal combustion engine. The clutch assembly 86 is mounted on an armsupport 88 which, in turn, is supported on the gear cover and engineblock for adjustable rotational positioning about an axis 90. The fanclutch assembly 86 may be rotated upwardly along the arc illustrated bydashed lines 92 in FIG. 2 into engagement at point 94 with camshaft gear18 to raise the position of the engine fan for certain engineapplications (such as automotive applications) which require the fan tobe placed well above the lowermost portion of the engine. Support arm 88also includes an internal lubrication flow path (not shown) to supplylubrication to the fan clutch assembly. Placement of the fan clutchassembly in the raised position just described wil require appropriatemodifications to the shape of the gear plate.

FIGS. 4 and 5 illustrate in detail the manner in which radial gear 22drives the oil pump, generally referred to at 95, which is integrallyhoused within the engine ladder frame 13, the operation of which isdescribed in U.S. patent application Ser. No. 90,478 filed Nov. 1, 1979,which was refiled as a continuation application on July 6, 1972, Ser.No. 337,406 both of which are assigned to the assignee of the presentapplication and entitled REVERSIBLE OIL PAN ASSEMBLY, the disclosure ofwhich is hereby incorporated by reference. Gear 22 is journaled on driveshaft 96 which is drivingly connected with a first pump element 98.First pump element 98 engages second pump element 100 which is mountedon countershaft 102. Pump elements 98 and 102 shown as gear impellersare rotatably mounted within a two part mounting frame or impellerhousing 104 positioned to extend into a recess 105 in engine ladderframe 13. Frame 104 as shown, is formed of an opensided housing part104b and a plate-like closure part 104c, and extends through an aperture104a contained in gear plate 10. Bolt 106 holds the sections of mountingframe 104 together and a plurality of mounting bolts 107 (only one ofwhich is illustrated in FIG. 4) affix the frame 104 to ladder frame 13.Frame 104 does not directly contact ladder frame 13 in any way eventhough recess 105 functions essentially as a housing for the oil pump.As explained in the aforementioned U.S. Patent Application entitledREVERSIBLE OIL PAN ASSEMBLY, oil is drawn from the oil pan through asump pipe connected with the oil pan and through a passage 109,illustrated in dashed lines, contained in ladder frame 13 wherein thepassage 109 is connected at one end 109a to the sump pipe and at theother end 109b to the suction side 108 of the oil pump by way of theillustrated clearance space (formed by the portion of recess 105 betweenthe two part housing 104 and the engine wall defining recess 105) andthe opening 104d shown in the closure part 104c. Upon being pressurizedby the pump, oil is delivered to the engine lubrication system throughpassage 110 in ladder frame 13. Passage 110 communicates with alubrication inlet (not shown) in the engine main frame (not shown).Crankshaft gear 14 drivingly engages idler gear 36 which in turndrivingly engages radial gear 22. The rotation of gear 22 activates pumpelements 98 and 100, causing oil to be drawn into oil pump 95 anddischarged from there into the engine lubrication system via a passage104e which is shown sealingly interconnected with passage 110 via agasket 111.

Two of the remaining accessory gears in the gear train, 28 and 30, andthe mounting supports therefor are illustrated in detail in FIG. 5 ofcopending application Ser. No. 974,562, filed on Dec. 29, 1978, thedisclosure of which is hereby incorporated by reference.

INDUSTRIAL APPLICABILITY

The gear plate and method of accurately positioning the plate of thisinvention finds its primary applicability in an internal combustionengine which utilizes a gear train to power engine accessories. Thistype of gear train is commonly used in compression ignition engines ofthe type employed in over-the-road vehicles. However, the subject gearplate may also be used advantageously in many other engine applicationssuch as portable compressor units and marine propulsion systems.

I claim:
 1. An oil pump arrangement for supplying oil under pressure inan internal combustion engine, which comprises in combination:aninternal combustion engine, one side of a portion of which is providedwith a recess in a planar end wall thereof; an oil pump having a twopart housing comprised of an open-sided housing part and a closure meansfor closing off the open side of said housing part, and wherein saidpump housing is of a size, relative to the size of said recess, forenabling said oil pump to be received within said recess with sufficientclearance to form a clearance space between said oil pump housing andwalls of the engine defining said recess, said clearance space forming asuction space for said oil pump; impeller gears which are provided insaid pump housing and which mesh with one another; driving meansoperatively connected to said internal combustion engine for driving atleast one of said impeller gears; a suction passage formed in the bodyof said internal combustion engine for providing communication betweensaid suction space and a source of oil, said pump housing including anopening for providing communication between said suction space and theinterior thereof; and a pressure passage means for communicating theinterior of said pump housing with said internal combustion enginecomprising a pressure passage formed in the body of said internalcombustion engine and opening into said recess, a passage formed throughsaid pump housing and means for interconnecting the pressure passage ofthe housing and the pressure passage of the engine body in a mannersealing-off said pressure passage means relative to said suction space.2. An oil pump arrangement according to claim 1, wherein the impellergears are rotatably mounted by both of said pump housing parts.